Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 14, 2233-2248, 2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
27 Aug 2014
Computational snow avalanche simulation in forested terrain
M. Teich2,1, J.-T. Fischer3, T. Feistl4,1, P. Bebi1, M. Christen1, and A. Grêt-Regamey2 1WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, 7260 Davos Dorf, Switzerland
2Planning of Landscape and Urban Systems PLUS, ETH Zurich, Stefano-Franscini-Platz 5, 8093 Zurich, Switzerland
3Austrian Research Centre for Forests – BFW, Department of Natural Hazards, Rennweg 1, 6020 Innsbruck, Austria
4Chair for Engineering Geology, Technical University Munich TUM, Arcisstrasse 21, 80333 Munich, Germany
Abstract. Two-dimensional avalanche simulation software operating in three-dimensional terrain is widely used for hazard zoning and engineering to predict runout distances and impact pressures of snow avalanche events. Mountain forests are an effective biological protection measure against avalanches; however, the protective capacity of forests to decelerate or even to stop avalanches that start within forested areas or directly above the treeline is seldom considered in this context. In particular, runout distances of small- to medium-scale avalanches are strongly influenced by the structural conditions of forests in the avalanche path. We present an evaluation and operationalization of a novel detrainment function implemented in the avalanche simulation software RAMMS for avalanche simulation in forested terrain. The new approach accounts for the effect of forests in the avalanche path by detraining mass, which leads to a deceleration and runout shortening of avalanches. The relationship is parameterized by the detrainment coefficient K [kg m−1 s−2] accounting for differing forest characteristics. We varied K when simulating 40 well-documented small- to medium-scale avalanches, which were released in and ran through forests of the Swiss Alps. Analyzing and comparing observed and simulated runout distances statistically revealed values for K suitable to simulate the combined influence of four forest characteristics on avalanche runout: forest type, crown closure, vertical structure and surface cover, for example, values for K were higher for dense spruce and mixed spruce-beech forests compared to open larch forests at the upper treeline. Considering forest structural conditions within avalanche simulations will improve current applications for avalanche simulation tools in mountain forest and natural hazard management.

Citation: Teich, M., Fischer, J.-T., Feistl, T., Bebi, P., Christen, M., and Grêt-Regamey, A.: Computational snow avalanche simulation in forested terrain, Nat. Hazards Earth Syst. Sci., 14, 2233-2248,, 2014.
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